How stars work
The ladder every skill is, twelve or twenty rungs by its grade, and why a star, once earned, is never taken away.
Every skill is a ladder of twelve or twenty rungs
A skill's ladder has twelve rungs for a skill from kindergarten to grade 3 and twenty for a skill from grade 4 to grade 8. It climbs in four blocks of equal length — three of facts and one of the skill used in a real question — where a right answer climbs one rung and a wrong one drops back to the start of the block, never below it, so a finished block is never lost.
The top rung is the star, and the last block is the proof it stuck: the skill used in real questions, with no slip. The next skill opens at the start of that block — rung 9 on twelve, rung 15 on twenty — so nobody waits on a star to move on.
Nothing takes a star away
The ladder is patient: stop mid-climb and it holds the rung for the next sitting, the next day or the next month. There is no timer, no leaderboard and no score out of ten — only the list of things they can now do, growing.
“In progress” on your pages is a skill mid-ladder, and the practice screen always shows which rung they stand on.